Bioprotective potential of bacteriocinogenic Enterococcus gallinarum strains isolated from some Nigerian fermented foods, and of their bacteriocins.

Enterococcus gallinarum strains isolated from some Nigerian fermented foods were found to produce bacteriocins. The bacteriocins had a broad spectrum of activity against both Gram-positive and negative bacteria. The effects of the bacteriocins and bacteriocinogenic organ- isms on Staphylococcus aureus infections in rats were evaluated. Sprague-Dawley rats were infected with S. aureus MTCC 737 and treated with E. gallinarum T71 and different concentrations of the bacteriocins from E. gallinarum W211 and T71. Staphylococcus aureus infection caused significant upregulation of aspartate aminotransferase and alanine aminotransferase levels in sera of the infected rats. Moreover, gelatin zymography revealed that infected gastric tissues showed elevated matrix metalloproteinase-9 activity. Bacteriocin treatments reduced the MMP-9 activity and inhibited the expressions of both Tumour Necrosis Factor Alpha (TNF-α) and Interleukin-1 Beta (IL-1ß) dose dependently, pointing to a potential role of the bacteriocins in attenuating inflammatory responses to Staphylococcus aureus infec- tion. Gastric and GIT damage caused by staphylococcal infection were reduced in the Enterococcus gallinarum T71 and bacteriocin-treated groups also dose dependently. We conclude that these bacteriocins may have useful biomedical applications.

Binding Capacities and Antioxidant Activities of Lactobacillus plantarum and Pichia kudriavzevii Against Cadmium and Lead Toxicities.

The cadmium and lead binding capacities and antioxidant activities of Lactobacillus plantarum and Pichia kudriavzevii were evaluated in vitro and in vivo. Lactic acid bacteria and yeasts obtained from fermenting cassava mash and maize slurry were screened for tolerance to cadmium and lead at 500-1050 mg ml-1 screened for probiotic potentials and antioxidant activities such as 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant properties. The in vivo studies were carried out in male Wistar rats. The strains identified as Lactobacillus plantarum ML05 and Pichia kudriavzevii FY05 demonstrated the best probiotic potentials and antioxidant activities. Alterations in antioxidant capacities were positive in the treatment groups. The histopathology displayed positive changes in the renal tubules and glomeruli, hypertrophy, with normal capsular spaces without inflammation in the kidney, while the liver sinusoids appear normal in the rats administered with L. plantarum ML05 and P. kudriavzevii FY05 while the infected and not treated showed cell necrosis induced by toxicities. Our results provided new evidence that Lactobacillus plantarum and Pichia kudriavzevii have different biological actions on the heavy metals binding capacities and antioxidant activities in experimental animals. This study suggests that these microorganisms can be considered dietary therapeutics against cadmium and lead toxicities.

Diversity of bacillus species isolated from okpehe, a traditional fermented soup condiment from Nigeria.

The diversity of Bacillus species isolated from the fermented soup condiment okpehe in Nigeria was studied using a combination of phenotypic and genotypic methods. Fifty strains presumptively characterized as Bacillus spp. using the API 50 CHB test were further identified by PCR of randomly amplified polymorphic DNA (RAPD) and by amplified ribosomal DNA restriction analysis (ARDRA) genotyping methods. ARDRA fingerprinting with HhaI, HinfI, and Sau3AI restriction enzymes did not allow successful differentiation between the Bacillus species, except for distinguishing B. cereus from other Bacillus species. This problem was overcome with the combination of RAPD PCR and ARDRA genotypic fingerprinting techniques. Sequencing of 16S rRNA genes of selected strains representative of the major clusters revealed that the Bacillus strains associated with this fermentation were B. subtilis, B. amyloliquefaciens, B. cereus, and B. licheniformis (in decreasing order of incidence). The presence of enterotoxin genes in all B. cereus strains was demonstrated by multiplex PCR. The high incidence of detection (20%) of possibly pathogenic B. cereus strains that contained enterotoxin genes indicated that these fermented foods may constitute a potential health risk.

Functional properties of selected starter cultures for sour maize bread.

This paper focuses on the functional properties of maize sour-dough microflora selected and tested for their use as starter cultures for sour maize bread. Lactic acid bacteria and yeasts isolated from spontaneously fermented maize dough were selected based on dominance during fermentation and presence at the end of fermentation. Functional properties examined included acidification, leavening and production of some antimicrobial compounds in the fermenting matrix. The organisms previously identified as Lactobacillus plantarum, Lb. brevis, Lb. fermentum, Lb. acidophilus, Pediococcus acidilactici, Leuconostoc mesenteroides and Leuconostoc dextranicum and Saccharomyces cerevisiae were used singly and as mixed cultures in the fermentation (fermentation time: 12h at 28+/-2 degrees C) of maize meal (particle size >0.2mm). The pH fell from an initial value of 5.62-3.05 in maize meals fermented with Lb. plantarum; 4.37 in L. dextranicum+S. cerevisiae compared with the value for the control (no starter) of 4.54. Significant differences (P

In vitro fermentation studies for selection and evaluation of Bacillus strains as starter cultures for the production of okpehe, a traditional African fermented condiment.

Selected Bacillus and Enterococcus strains, isolated from traditional okpehe fermentations, were studied for their suitability as starter cultures in laboratory-scale fermentations of Prosopis africana seeds for the production of okpehe, a traditional fermented vegetable product of Nigeria. The strains were selected on the basis of highest proteolytic activity, as determined with the APIZYM (BioMerieux) test. The choice of starter strains was narrowed to Bacillus subtilis strains BFE 5301 and BFE 5372. These were determined as the best starter combination because of rapid growth, high amylolytic and proteolytic activities, high levels of polyglutamic acid production by strain BFE 5372, as well as bacteriocin production by strain BFE 5301. Other mixed culture fermentations did not yield sensorically acceptable products. Although a monoculture fermentation, using only B. subtilis strain BFE 5372, produced okpehe with very good sensory characteristics, the growth of B. cereus could be detected after 48 h fermentation, indicating that this starter did not sufficiently contribute to product safety. Mixed culture fermentation with the combination of bacteriocin-producing starter B. subtilis BFE 5301 and the non-bacteriocin-producing B. subtilis BFE 5372, produced a product with good sensory characteristics, in which growth of B. cereus was delayed. The bacteriocin produced by B. subtilis strain BFE 5301 was identified as subtilisin, using subtilisin-specific primers and PCR amplification of the subtilisin gene. The bacteriocin was heat-stable at 100 degrees C for 10 min and exhibited highest activity at pH values lower or equal to pH 6.0. The bacteriocin was sensitive to the proteolytic enzymes trypsin and alpha-chymotrypsin at concentrations of 10 mg/ml.

Development of cereal-based functional food using cereal-mix substrate fermented with probiotic strain - Pichia kudriavzevii OG32.

Probiotic strains contribute to the functionality of foods during fermentation. In this present work, cereal-mix was fermented with probiotic Pichia kudriavzevii OG32. Selected fermentation parameters and functional properties of the product were determined. The growth of Pichia kudriavzevii OG32 was supported by the cereal-mix containing 1% salt and 0.2% red chili powder to counts of between 7.46 and 8.22 Log10 cfu/mL within 24 h. Pichia kudriavzevii OG32 increased the viscosity of cereal-mix with the highest inoculum size (1.84x105cfu/ml) giving the highest viscosity of 1793.6 mPa.S. An inoculum size of 1.98 × 10(4) cfu/mL gave the most acceptable product based on the sensory evaluation by the panelist. Forty volatile compounds were identified in the fermented product, while acids (32.21%) and esters (32.37%) accounted for the largest proportions. The cereal-based fermented product scavenged DPPH from 200 µmol/L methanolic solution by 55.71%. Probiotic yeast improved the sensory and some functional properties of cereal-based substrate during fermentation. This is one of the first reports on the volatile composition of cereal-based functional food produced with probiotic yeast.